Ironbark, Grey

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Grey ironbark is a premium native hardwood that has been well regarded as a high quality timber in Australia throughout human history. Indigenous Australians use it to make spear throwers and boil its bark for treating sores.

It is a particularly hard, strong and durable timber, with a broad range of applications, due to its resistance to lyctid borers and termites.

The grey ironbark is a medium sized tree of 30 to 50m with a stem diameter of 1.5m. The bark is hard, coarse, with deep furrows and ridges, ranging from dark brown to black in colour and grows even on the small branches.

E. drepanophylla is found from northern New South Wales to Bundaberg, Queensland. It is also found in scattered patches as far north as the Atherton Tableland. E. paniculata is found in New South Wales only from Bega to Coffs Harbour.

A very heavy timber, at 1120 kilograms per cubic metre, grey ironbark is dense and can be difficult to work. Dressed surfaces take on a steely sheen.

The timber's appearance ranges from reddish to dark brown heartwood. The sapwood is lighter in colour and is 20mm thick on average. Grain is usually tight and straight and no distinctive figure is encountered.

Both sawn and round grey ironbark timber have a wide range of applications. Engineering uses include railway sleepers, construction, poles and cross-arms, and bridge construction. Unseasoned timber is used in house framing, while dressed timber can be employed for both internal and external use. It has also been used in boat, coach, vehicle and carriage building and to create sporting goods.

 

Appearance

Grey ironbark sapwood is almost white, making it highly distinct from the heartwood, that ranges from light grey or light chocolate with occasional darker reds and browns. The texture is moderately coarse and even, and the grain usually straight, and only occasionally interlocked. Grey Ironbark may have regional variations in colour, with some having black narrow to broad streaks running through the timber.

Common Applications

Due to its class 1 strength and durability ratings, grey ironbark is commonly used in engineering applications as a sawn and round timber. It can be specified for wharf and bridge construction, railway sleepers, cross arms, poles, piles and mining timbers.

The unseasoned timber is excellent for general house framing, while seasoned and dressed grey ironbark timber is used for cladding, internal and external flooring, linings and joinery. It is also ideal for fencing, landscaping and retaining walls.

The timber's versatility extends to boat building (keel and framing components, planking), including reputed use in the hulls of early ice-breaker ships. Coach, vehicle and carriage building, agricultural machinery, mallet heads, mauls and bearings, sporting goods (croquet mallets, parallel bars) and bowling ninepins have all been made from grey ironbark.

Common Form

Sawn

Workability

Grey ironbark has been employed for decorative purposes such as in outdoor furniture, turning and joinery, although its density makes it hard to work in applications requiring fine detail.

It is slow drying and should be handled carefully to avoid surface checking.

Origin of Timber

NSW

Readily Available

NSW

Availability - Further Information

Grey Ironbark is common to coastal regions of NSW and in southern Queensland. E paniculata is the most common commercial species of Ironbark timber. It is not generally available in a range of sizes, but can be supplied to order. Large sizes in particular are commonly ordered for structural uses, so it is more readily available in this form

Shrinkage

Very Low Low Medium High Very High

Tangential :

7.50%

Radial:

4.70%

Unit Movement Tangential:

0.39%

Unit Movement Radial:

0.31%

Strength Group

Very High

High

Reasonably High

Medium High

Medium

Reasonably Low

Low

Very Low

Unseasoned:

S1

S2

S3

S4

S5

S6

S7

Seasoned:

SD1

SD2

SD3

SD4

SD5

SD6

SD7

SD8

Stress Grade

Structural
No. 1
Structural
No. 2
Structural
No. 3
Structural
No. 4
Structural
No. 5

Unseasoned:

F22

F22

F17

F14

F11

Seasoned:

F34

F34

F27

F22

F17

Density per Standard

Seasoned:

1106kg/m3

Unseasoned:

1170kg/m3

Joint Group

Very High

High

Reasonably High

Medium

Low

Very Low

Unseasoned:

J1

J2

J3

J4

J5

J6

Seasoned:

JD1

JD2

JD3

JD4

JD5

JD6

Colour

  White, yellow, pale straw to light brown Pink to pink brown Light to dark red Brown, chocolate, mottled or streaky
   

Mechanical Properties

Modulus of Rupture - Unseasoned:

121

Modulus of Rupture - Seasoned:

185

Modulus of Elasticity - Unseasoned:

19

Modulus of Elasticity - Seasoned:

23

Maximum Crushing Strength - Unseasoned:

63

Maximum Crushing Strength - Seasoned:

97

Impact - Unseasoned:

27

Impact - Seasoned:

25

Toughness - Unseasoned:

High - 25 Nm and above

Toughness - Seasoned:

High - 25 Nm and above

Hardness - Unseasoned:

11

Hardness - Seasoned:

16

Durability

Low Moderate Reasonably High High
(0 - 5 yrs) (5 - 15 yrs) (15 - 25 yrs) (more than 25 yrs)

In-Ground:

(0 - 7 yrs) (7 - 15 yrs) (15 - 40 yrs) (More than 40 yrs)

Above ground:

(0 - 20 yrs, usually < 5) (21 - 40 yrs) (41 - 64 yrs) (More than 60 yrs)

Marine Borer Resistance:

Lyctid Borer Susceptibility:

Not Susceptible

Lyctid Borer Susceptibility - Other:

Termite Resistance:

Resistant

Fire Properties

0 1 2 3 4 5 6 7 8 9 10

EFH Spread-of-Flame Index:

EFH Smoke-Developed Index:

Critical Radiance Flux - Lower:

>2.2 and <4.5

Critical Radiance Flux - Higher:

≥4.5

Smoke Development Rate:

<750
1 - non-combustible 2 - reasonably non-combustible 3 - slightly combustible 4 - combustible

Fire Properties Group
Number:

Average Specific Extinction Area:

<250

Bushfire Resistance:

BAL 12.5 and 19 – All AS3959 required applications

Joinery

Timber joinery products offer a classic, unique and stylish touch to any interior or exterior design. The products are produced for a variety of internal applications including door and window frames, cabinetry, skirtings, mouldings and architraves. When looking to the outdoors, joinery products range from decorative eaves and posts to eye-catching railings.

Many timber species are suitable for joinery products and care should be taken in selecting the perfect timber for the particular product and its intended finish. Rare and exotic species such as Teak and Rosewood can generate pieces of outstanding beauty but material cost and availability are also important considerations.

Commercially available species like Tasmanian oak, Australian cypress, spotted gum and the like, often make the more practical choice, with the added benefit that they can be easily matched with other timber products within the building, like flooring.

Solid timber for joinery products is generally supplied as ‘clear finish grade' but ‘paint grade' options are available and these are usually comprised of a composite material like MDF or glulam.

A large number of specialist suppliers and producers offer the consumer extensive choice of profiles for all of the most common and popular joinery products. Choice is in many cases, limited only by imagination.

Cabinetry is often associated with joinery and most typically includes, cupboards, benches and other similar ‘built in' furniture. Like joinery, cabinetry is generally specified as either paint or clear finish grade and naturally for clear finish grade timbers, appearance and surface finish are critical in achieving a successful application.

 

Decking

Download the WoodSolutions Technical Design Guide on Domestic Timber Decking here.

Timber decks are a practical and attractive addition to any outdoor landscape. Natural timber decks blend seamlessly with their surrounding environment and will serve as popular entertaining areas all year long.

As an external structure, carrying large loads of traffic, timber decking has high structural performance requirements. In addition decks are usually raised clear off the ground and fully exposed to the weather meaning an effective deck must be able to cope with wear and tear from repeated use and in addition discharge rainwater efficiently. Roundin the corners (easing the arris) of the decking will help run off water while spacing for ventilation between the decking boards will prevent water ponding on the deck surface. 

Timber decking is available in both seasoned and unseasoned wood, in a wide range of species, sizes and grades. The natural appeal and strength of timber makes it a practical choice for outdoor decking. This guide provides an overview of best practice methods for specifying, installing and finishing a timber deck.

Fencing

The inherent appeal and strength of timber makes it the obvious choice for fencing. Timber fencing not only provides a natural look in keeping with the outdoor environment but it also enables the construction of a long lasting, durable property boundary. Fences come in many forms including the traditional paling, picket, post and railing styles. Most rely on a structural frame of posts embedded into the ground and two or more rails spanning between the posts. The ultimate selection of a suitable fence type or style is determined by application and aesthetics. A fence can serve a variety of purposes, including the provision of security, privacy and safety in addition to defining property boundaries. Specification for durability is important, especially for posts, given their exposure to high moisture in the ground.

This section provides an overview to best practice methods in specifying, installing and finishing a timber fence.

Mouldings

Timber mouldings add style, class and an elegant touch to any interior, offering a depth of beauty and warmth in a way only wood can. From period times to those more contemporary, timber mouldings have graced the most stylish and chic of interiors, decorating furniture, doors and windows. Decorative mouldings such as architraves, skirtings, cornices and ceiling roses remain an ever popular choice for designers seeking a finished result of beauty, style and quality. Like all timber products, mouldings are extremely versatile and durable, enhancing the aesthetics of any interior and functioning as the perfect finishing touch for designs with a focus on beauty and splendour.

Mouldings can be created from any commercially available species of timber and the moisture resistant wood product, MDF, is also a popular choice. When it comes to style and design, the sky is the limit with many suppliers offering custom matching to existing mouldings, as well as efficient supply of those that are individually designed. Installation is a breeze, with the majority of mouldings easily attached with a reputable wood adhesive. Finishes can be tailored by design requirements and the preferences of the end user, with mouldings commonly being both stained and/or painted.

Retaining Walls (Landscaping)

The natural appeal, strength and versatility of timber makes it an ideal choice for retaining wall landscaping applications.

Retaining wall systems include cantilevered round or sawn timber, mass wall and crib wall construction. Walls up to one metre in height follow a basic design and can usually be constructed using standard proprietary wall systems. An engineer will be required to plan and design walls greater than one metre, including the footings and drainage.

Drainage of retaining walls is a critical factor in influencing the long term stability of the wall and should thus form a significant part of the design and planning process. 

Regular care and maintenance of retaining walls is essential in ensuring the long-term stability and safety of the structure.

Structural Timber Poles

Timber pole construction is typically utilised to provide support for gravity loads and resistance against lateral forces. The natural appeal of timber ensures that its role is not purely structural however, with timber poles complimenting architectural designs aimed at harmonisation with the natural environment. The small number of footings required in pole frame construction also ensures minimal disturbances to the site.

With a double bearer system, poles can be spaced further apart than is usual, creating a more spacious building interior, that allows greater interior design flexibility. While poles are usually placed in a grid like system this is not compulsory and the flexibility of the application means the system can cope with a wide variety of designs, enabling designers to take full advantage of beautiful outlooks.

This article provides a comprehensive overview of the process involved in specifying, designing and constructing a solid timber pole construction.

Flooring

Whether for structural or finished flooring applications, timber offers durability, versatility and adaptability. The warmth, strength and natural beauty of timber flooring has proved enduringly popular in a wide variety of interior settings.

Timber flooring is a timeless product, offering a warmth and natural beauty largely unmatched by other flooring options. This article provides an overview of the installation of solid timber strip flooring over bearers and joists, timber based sheet flooring products and concrete slabs. Timber flooring is typically supplied as either solid timber or laminated wood products, made from layers of bonded timber. It fits together with a tongue and groove joint and once in place, is sanded and finished. There is a wide variety of species to select flooring from and the right species for a given application will be dependent on numerous factors. Information relating to species selection, environmental assessment, finish selection and recommended maintenance routines are all provided in this section.

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